Field of the Invention:
The invention relates to a method for producing a conductor bar of a stator winding for an electric machine, in particular a generator, with a stator as well as a rotor disposed rotatably therein. Each conductor bar is formed from component conductors which are made of conductive material, are situated one above another in pairs, traverse a stack from a top layer obliquely to a bottom layer and in each case have uniform cranks in the vicinity of the top layer and in a bottom region. The cranks of each two component conductors placed one above another and assigned to one another in pairs are disposed offset in the longitudinal direction at a spacing relative to cranks of a succeeding or preceding pair of component conductors. The component conductors are disposed in two stacks located next to one another and laterally adjoining one another. The component conductors are each situated one above another in pairs and in each case are mutually interlocked through the use of the laterally neighboring component conductors. As a result, each conductor bar extends partially on the surface of the stator facing toward and away from the rotor. The invention also relates to a conductor bar for such a stator winding which is produced according to the method.
It is known in the case of large electric machines, in particular of rotary machines such as motors or generators, which have a stator and a rotor rotatably disposed therein, for the windings disposed in the stator and in the rotor to be configured by using conductor bars with a large rectangular cross section made from electrically conducting material, such as copper.
In that structure, because of the large cross section per conductor bar required in each case, the individual conductor bars are formed from component conductors which are usually disposed in each case one behind another radially with interposed insulation in two stacks located next to one another.
In order to avoid, or at least to reduce an increase in resistance due to the displacement of current from the interior of the conductor to the surface thereof, the individual conductors are usually provided with uniform cranks which have the effect of causing each component conductor bar to run partly along the surface of the conductor.
In that regard, the word crank is understood as a double bending of the individual component conductor of a conductor bar which permits each individual conductor to be joined partly to the other component conductors inside the conductor bar in such a way that the component conductor runs alternately in one or the other, adjoining conductor stack. The individual component conductors are interlocked helically so that it can occur continuously. In that configuration, each component conductor runs in sections in the same relationship in the planes of the winding which is provided.
That possibility for reducing resistance has been successfully employed for a long time. However, it has now emerged that in the case of electrical machines of higher power, in which each conductor bar must have a relatively large current-carrying capacity, such interlocking or offsetting encounters limits of feasibility which can only be reached by a different dimensioning of the component conductors.
The result thereof, on one hand, is that when producing the component conductors for a conductor bar there is a specific need for space for the finished or offset component conductors, and that need results from the radius of curvature for the crank. On the other hand, the space available in the stator is insufficient for the volume required by the finished offset conductor bars. The consequence so far has been an increased outlay for production in order to nevertheless be able to install the conductor bars provided in the available space.